Abstract:

A sealing device having a dust filter, in which sliding torque due to the
dust filter is reduced with dust sealing performance of the dust filter
maintained at a high level. The sealing device is provided with a seal
lip (12) mounted to a non-rotating housing (200) and made to be in
slidable close contact with a rotation-side member (2), and the sealing
device is also provided with the dust filter (16) located closer to the
atmosphere (A) than the seal lip (12) and having an inner diameter
section (16a) which is made to be in slidable close contact with the
outer peripheral surface of the rotation-side member (2). Cutouts (16b)
are formed at predetermined circumferential intervals in the inner
diameter section (16a) of the dust filter (16), and the deepest sections
of the cutouts (16b) have an appropriate allowance for fastening to the
outer peripheral surface of the rotation-side member (2).

Claims:

1. A sealing device comprising:a seal lip attached to a non-rotating
housing and slidably brought into close contact with a rotation-side
member; anda dust filter located closer to an atmosphere side than the
seal lip and having an inner diameter section slidably brought into close
contact with an outer peripheral surface of said rotation-side
member,wherein a plurality of cutouts are formed in the inner diameter
section of said dust filter at a predetermined circumferential interval,
and an edge portion of a deepest section in each of said cutouts is in
close contact with the outer peripheral surface of said rotation-side
member with a suitable fastening margin.

2. A sealing device comprising:a seal lip attached to a non-rotating
housing and slidably brought into close contact with a rotation-side
member; anda dust filter located closer to an atmosphere side than the
seal lip and having an inner diameter section slidably brought into close
contact with an outer peripheral surface of said rotation-side
member,wherein a plurality of slits are formed in the inner diameter
section of said dust filter at a predetermined circumferential interval,
and an edge portion of a deepest section in each of said slits is in
close contact with the outer peripheral surface of said rotation-side
member with a suitable fastening margin.

Description:

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001]This is a national stage of the International Application No.
PCT/JP2009/057047 filed on Apr. 6, 2009 and published in Japanese
language.

BACKGROUND OF THE INVENTION

[0002]1. Field of the Invention

[0003]The present invention relates to a sealing device sealing an outer
periphery of a rotating body, and more particularly to a sealing device
provided with a dust filter at an atmosphere side.

[0004]2. Description of the Conventional Art

[0005]In a sealing device used as an engine seal of a motor truck or the
like, a structure having a dust filter is used (refer, for example, to
the following patent document).

[0007]FIG. 5 is a half cross sectional view in an installed state showing
this kind of conventional sealing device by being cut along a plane
passing through an axis. A sealing device 100 shown in FIG. 5 is provided
with a seal main body 110 attached to a housing 200, and a metal slinger
120 attached to a rotating shaft 300 inserted to an inner periphery of
the housing 200. The seal main body 110 is provided with a metal
attaching ring 111 which is pressure inserted and fitted to an inner
peripheral surface of the housing 200, a seal lip 112 integrally formed
by a rubber material or a material having a rubber-like elasticity in the
attaching ring 111 and being slidably brought into close contact with a
flange 121 of the slinger 120, and a dust filter 113 provided closer to
an atmosphere A side than the seal lip 112,and having an inner diameter
section which is slidably brought into close contact with an outer
peripheral portion of the sleeve 122 of the slinger 120 in a state of
being bent to the atmosphere A side, and made of a non-woven fabric of a
synthetic resin fiber.

[0008]The seal lip 112 is structured such that its leading end is brought
into close contact with the flange 121 of the slinger 120, thereby
preventing a sealed subject oil close to a sealed space B side from
leaking to the atmosphere A side, and since the slinger 120 has a
function of throwing off such a fluid that comes into contact with the
flange 121 to an outer peripheral side on the basis of a centrifugal
force, it achieves an excellent sealing function against the sealed
subject oil which is going to pass through a sliding portion S with the
seal lip 112 to an inner peripheral side. Further, the dust filter 113 is
structured such as to inhibit the dust from making an intrusion into an
inner peripheral space C of the seal lip 112 which comes to a low
pressure on the basis of the throwing-off function mentioned above from
the atmosphere A side.

[0009]In this case, in recent years, in the light of regulation of fuel
consumption of a motor vehicle, a further reduction of a sliding torque
is required in this kind of sealing device 100. Further, in the sliding
torque generated in this kind of sealing device 100, about one third to
one half is caused by a sliding motion between the dust filter 113 and
the sleeve 122 of the slinger 120. Accordingly, in order to reduce the
sliding torque, it is considered to employ a structure having no dust
filter 113, or having the dust filter 113 with a reduced thickness to
make a tension force applied to the sleeve 122 smaller.

[0010]However, in the case that the dust filter 113 is not employed or
made thin, the dust coming close to the atmosphere A side makes an
intrusion into the inner peripheral space C of the seal lip 112 coming to
the low pressure on the basis of the throwing-off function of the flange
121 so as to be bitten into a sliding portion S between the seal lip 112
and the flange 121 of the slinger 120, thereby causing a reduction of a
durability of the seal lip 112. Alternatively, there is another risk that
the dust makes an intrusion into the sealed space B from the inner
peripheral space C of the seal lip 112 on the basis of the throwing-off
function of the flange 121 of the slinger 120.

[0011]Further, the sealing device 100 shown in FIG. 5 is structured such
that a protrusion 123 formed at an end portion opposite to the flange 121
in the sleeve 122 can engage with an inner diameter section of the dust
filter 113, in a state in which the sealing device 100 is not installed
to the housing 200 and the rotating shaft 300, whereby it is possible to
temporarily assemble the slinger 120 with respect to the seal main body
110 in a come-off preventing state, however, if the dust filter 113 is
not employed or is formed thin, there is pointed out such a problem that
the temporary assembly mentioned above can not be achieved.

SUMMARY OF THE INVENTION

Problem to be Solved by the Invention

[0012]The present invention is made by taking the points mentioned above
into consideration, and a technical object of the present invention is to
reduce a sliding torque caused by a dust filter in a state in which a
dust sealing property generated by the dust filter is secured, in a
sealing device provided with the dust filter.

Means for Solving the Problem

[0013]In order to effectively achieve the technical object mentioned
above, in accordance with a first aspect of the present invention, there
is provided a sealing device comprising:

[0014]a seal lip attached to a non-rotating housing and slidably brought
into close contact with a rotation-side member; and [0015]a dust filter
located closer to an atmosphere side than the seal lip and having an
inner diameter section slidably brought into close contact with an outer
peripheral surface of the rotation-side member,

[0016]wherein a plurality of cutouts are formed at a predetermined
circumferential interval in the inner diameter section of the dust
filter, and an edge portion of a deepest section in each of the cutouts
has a suitable fastening margin with respect to the outer peripheral
surface of the rotation-side member.

[0017]In accordance with the structure mentioned above, since a plurality
of cutouts are formed at the predetermined circumferential interval in
the inner diameter section of the dust filter, a tension force of the
dust filter with respect to the outer peripheral surface of the
rotation-side member is reduced, and a sliding area of the dust filter
with respect to the outer peripheral surface of the rotation-side member
becomes smaller due to the provision of the cutouts. Accordingly, a
sliding torque is lowered. Further, since the edge portion of the deepest
section in each of the cutouts has the suitable fastening margin with
respect to the outer peripheral surface of the rotation-side member, a
gap is not generated by the cutouts with respect to the outer peripheral
surface of the rotation-side member, and the dust filter is not made
thin. Accordingly, a desired dust sealing performance can be secured.

[0018]Further, in accordance with a second aspect of the present
invention, there is provided a sealing device comprising:

[0019]a seal lip attached to a non-rotating housing and slidably brought
into close contact with a rotation-side member; and

[0020]a dust filter located closer to an atmosphere side than the seal lip
and having an inner diameter section slidably brought into close contact
with an outer peripheral surface of the rotation-side member,

[0021]wherein a plurality of slits are formed at a predetermined
circumferential interval in the inner diameter section of the dust
filter, and an edge portion of a deepest section in each of the slits has
a suitable fastening margin with respect to the outer peripheral surface
of the rotation-side member.

[0022]In accordance with this structure, since a plurality of slits are
formed at the predetermined circumferential interval in the inner
diameter section of the dust filter, a tension force of the dust filter
with respect to the outer peripheral surface of the rotation-side member
is reduced. Accordingly, a sliding torque is lowered. Further, since the
edge portion of the deepest section in each of the slits has a suitable
fastening margin with respect to the outer peripheral surface of the
rotation-side member, a gap is not generated by the slits with respect to
the outer peripheral surface of the rotation-side member, and the dust
filter is not made thin. Accordingly, a desired dust sealing performance
can be secured.

Effect of the Invention

[0023]In accordance with the sealing device on the basis of the present
invention, since the dust sealing performance obtained by the dust filter
can be secured, it is possible to reduce the sliding torque generated by
the dust filter without sacrificing a sealing durability.

BRIEF EXPLANATION OF DRAWINGS

[0024]FIG. 1 is a half cross sectional view in an installed state showing
a sealing device in accordance with a first embodiment of the present
invention by being cut along a plane passing through an axis;

[0025]FIG. 2 is a half cross sectional view in an uninstalled state
showing the sealing device in FIG. 1 by being cut along the plane passing
through the axis;

[0026]FIG. 3 is a view of a dust filter used in the sealing device in FIG.
1 as seen from an extending direction of the axis;

[0027]FIG. 4 is a half cross sectional view in an installed state showing
a sealing device in accordance with a second embodiment of the present
invention by being cut along a plane passing through an axis; and

[0028]FIG. 5 is a half cross sectional view in an installed state showing
a sealing device in accordance with a prior art by being cut along a
plane passing through an axis.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

[0029]A description will be in detail given below of a preferable
embodiment of a sealing device in accordance with the present invention
with reference to the accompanying drawings. FIG. 1 is a half cross
sectional view in an installed state showing a sealing device in
accordance with a first embodiment of the present invention by being cut
along a plane passing through an axis, FIG. 2 is a half cross sectional
view in an uninstalled state showing the sealing device in FIG. 1 by
being cut along the plane passing through the axis, and FIG. 3 is a view
of a dust filter used in the sealing device in FIG. 1 as seen from an
extending direction of the axis.

[0030]In FIG. 1, reference numeral 200 denotes a non-rotating housing in
an engine or the like of a motor truck, and reference numeral 300 denotes
a rotating shaft inserted to an inner periphery of the housing 200. The
sealing device in accordance with the present invention is provided with
a seal main body 1 attached to the housing 200, and a slinger 2 attached
to the rotating shaft 300. In this case, the slinger 2 corresponds to a
rotation-side member described in the first aspect of the invention.

[0031]The seal main body 1 is provided with an installation ring 11 which
is pressure inserted and fitted to an inner peripheral surface of the
housing 200, a seal lip 12, a gasket portion 13, an oil return portion 14
and an elastic layer 15 extending continuously therebetween which are
integrally formed in the installation ring 11, and a dust filter 16 which
is positioned closer to an atmosphere A side than the seal lip 12 and is
attached to an inner diameter section of the elastic layer 15.

[0032]The installation ring 11 is manufactured by punching press working a
metal plate such as a steel plate or the like, and is constructed by an
outer peripheral fitting portion 11a which is pressure inserted and
fitted to an inner peripheral surface of the housing 200, a gasket
support portion 11b which is formed with a step having a slightly smaller
diameter in a direction coming to the atmosphere A side from the outer
peripheral fitting portion 11a, a radially extending portion 11c which
extends to an inner peripheral side therefrom, a conical tubular portion
11d which extends to a sealed space B side from an inner periphery
thereof, and an inward collar portion 11e which further extends to an
inner peripheral side from an end portion thereof.

[0033]The seal lip 12, the gasket portion 13, the oil return portion 14
and the elastic layer 15 are made of a rubber material or a synthetic
resin material having a rubber-like elasticity. Among them, the elastic
layer 15 is integrally vulcanized and bonded in such a manner as to coat
an outer surface (a surface directed to atmosphere A side) of the
installation ring 11, and the seal lip 12 is formed in a tapered shape
that its leading end is directed to an outer peripheral side so as to
extend to the sealed space B side, from an inner diameter section of the
elastic layer 15. Further, the gasket portion 13 is positioned in an
outer periphery of the gasket support portion 11b of the installation
ring 11, and is continuously formed with an outer diameter section of the
elastic layer 15. Further, the oil return portion 14 is formed in an
inner diameter section of the elastic layer 15, and is formed in a gutter
shape that its leading end is directed to the seal lip 12 side.

[0034]The dust filter 16 is made by a non-woven fabric of a synthetic
resin fiber, and an outer diameter section thereof is located closer to
atmosphere A side than the seal lip 12, i.e. located at an outer side of
the inward collar portion 11e of the installation ring 11 so as to be
bonded to the elastic layer 15.

[0035]The slinger 2 is manufactured by punching press working a metal
plate, and has a sleeve 21 which is closely fitted to an outer peripheral
surface of the rotating shaft 300, a flange 22 which expands in a disc
shape from an end portion close to the sealed space B side, and a
protrusion 23 formed at an end portion close to the atmosphere A side in
the sleeve 21 so as to be bent to an outer diameter side. The seal lip 12
of the seal main body 1 is slidably brought into close contact in its
leading end and its vicinity with an end surface directed to an opposite
side to the sealed space B side of the flange 22 in the slinger 2 so as
to form a sliding portion S, and the dust filter 16 is structured such
that an inner diameter section 16a is slidably brought into close contact
with an outer peripheral surface of the sleeve 21 in the slinger 2.

[0036]A plurality of cutouts 16b are formed at a predetermined
circumferential interval in the inner diameter section 16a of the dust
filter 16. Further, the dust filter 16 forms a plane which is orthogonal
to an axis in an uninstalled state shown in FIGS. 2 and 3, and in this
state, an inner diameter φ1 of a deepest section in each of the
cutouts 16b is larger than an inner diameter φ2 of the dust filter 16
and is slightly smaller than an outer diameter φ3 of the sliding
portion with the dust filter 16 in the sleeve 21 of the slinger 2.
Further, an outer diameter of the protrusion 23 formed at an end portion
of the sleeve 21 of the slinger 2 is set to such an extent that can pass
through while suitably pushing open the inner diameter section 16a of the
dust filter 16, at a time of inserting the slinger 2 as shown by an arrow
of the bold line in FIG. 2.

[0037]Accordingly, by inserting the sleeve 21 of the slinger 2 to the
inner periphery of the seal main body 1 from a separated state shown in
FIG. 2, the inner diameter section 16a of the dust filter 16 is brought
into close contact with the outer peripheral surface of the sleeve 21 in
a state of being suitably pushed open, and the edge portion 16c of the
deepest section in each of the cutouts 16b is brought into close contact
with the outer peripheral surface of the sleeve 21 with a suitable
fastening margin, as shown in FIG. 1.

[0038]The sealing device provided with the above mentioned structure is
configured, as shown in FIG. 1, such that the seal main body 1 is
pressure inserted and fitted to the inner peripheral surface of the
housing 200 in the outer peripheral fitting portion 11 a of the
installation ring 11, and is closely fitted with the suitable collapsing
margin in the gasket portion 13, and the seal lip 12 of the seal main
body 1 comes into slidably close contact with the flange 22 of the
slinger 2 which is integrally rotated with the rotating shaft 300,
thereby inhibiting a sealed subject oil flying from the sealed space (for
example, a crank chamber of an engine) B side from leaking to the
atmosphere A side. Further, since the slinger 2 has an effect of throwing
off a fluid coming into contact with the flange 22 to an outer diameter
direction on the basis of a centrifugal force, it achieves an excellent
sealing function with respect to the sealed subject oil which is going to
pass through the sliding portion S with respect to the seal lip 12 to an
inner peripheral side.

[0039]Further, in case that the sealed subject oil slightly passes through
the sliding portion S between the seal lip 12 and the flange 22 of the
slinger 2 to the inner peripheral side, the leaking fluid flows downward
along the tapered surface 12a and is received by the gutter-shaped oil
return portion 14, in an upper half portion side of the seal lip 12.
Further, since the leaking fluid flows within the oil return portion 14
toward its lower half portion side, and runs down to an outer diameter
side (a downward side) of the seal lip 12 along the surface 12a in the
lower half portion of the seal lip 12, it is thrown off to the outer
diameter side from the sliding portion S with respect to the flange 22 on
the basis of a centrifugal force so as to be excluded.

[0040]In this case, as mentioned above, since the flange 22 of the slinger
2 has the effect of discharging the fluid from the sliding portion S to
the outer diameter side on the basis of the centrifugal force at a time
of rotating, a negative pressure is generated in the inner peripheral
space C of the seal lip 12, whereby the dust is going to flow into the
inner peripheral space C together with the air from the atmosphere A
side, however, since the dust is captured by the dust filter 16 made by
the non-woven fabric of the synthetic fiber, it is possible to inhibit
the dust from making an intrusion into the inner peripheral space C.

[0041]Further, in the inner diameter section 16a of the dust filter 16,
since a plurality of cutouts 16b are formed at a predetermined
circumferential interval, a tension force with respect to the outer
peripheral surface of the sleeve 21 of the slinger 2 is held down.
Further, the sliding area of the dust filter 16 with respect to the outer
peripheral surface of the sleeve 21 becomes smaller by the cutouts 16b.
Accordingly, since the sliding torque of the dust filter 16 is lowered,
and the sliding torque as a whole of the sealing device is lowered, it is
possible to contribute to an improvement in the specific fuel
consumption.

[0042]Further, since the inner diameter section 16a of the dust filter 16
is brought into close contact with the outer peripheral surface of the
sleeve 21 of the slinger 2 with the suitable fastening margin, even in
the edge portion 16c of the deepest section in the cutouts 16b, a gap is
not generated with respect to the outer peripheral surface of the sleeve
21 by the cutouts 16b, and the dust filter 16 is not made thin for
lowering the torque. Accordingly, a desired dust sealing property can be
secured.

[0043]Further, since the protrusion 23 and the inner diameter section 16a
of the dust filter 16 are opposed to each other in the axial direction in
a state in which they can be engaged with each other, once the protrusion
23 formed at the end portion of the sleeve 21 passes through the inner
diameter section 16a while suitably pushing open the inner diameter
section 16a of the dust filter 16, by inserting the sleeve 21 of the
slinger 2 to the inner periphery of the seal main body 1, from the
separated state shown in FIG. 2, it is possible to temporarily assemble
the seal main body 1 and the slinger 2 in a come-off preventing state.
Further, in accordance with the present invention, since it is not
necessary to make the dust filter 16 thin for lowering the torque as
mentioned, it is possible to secure a desired engaging force with the
protrusion 23 by the inner diameter section 16a of the dust filter 16
which is brought into close contact with the outer peripheral surface of
the sleeve 21 with the suitablefastening margin, and it is possible to
prevent the seal main body 1 and the slinger 2 from being separated, for
example, in a transporting process in a temporary assembled state.

[0044]In this case, in the embodiment mentioned above, the structure is
made such that the seal lip 12 and the dust filter 16 are slidably
brought into close contact with the slinger 2 serving as the
rotation-side member, however, the present invention can be applied to a
structure in which the seal lip 12 and the dust filter 16 are slidably
brought into close contact with the outer peripheral surface of the
rotating shaft 300 serving as the rotation-side member, and the material
of the seal lip 12 or the like is not particularly limited.

[0045]Further, a shape of the cutout 16b can be considered to be a
semicircular shape, a U-shaped form, a V-shaped form, a wave form and the
like in addition to the C-shaped form in section as illustrated, and is
not particularly limited.

[0046]FIG. 4 is a half cross sectional view in a installed state showing a
sealing device in accordance with a second embodiment of the present
invention by being cut along a plane passing through an axis.

[0047]The second embodiment is structured such that a plurality of slits
16d extending in a radial direction are formed at a predetermined
circumferential interval, in place of a plurality of cutouts 16b in the
first embodiment described previously, in the inner diameter section 16a
of the dust filter 16. Further, the dust filter 16 is formed as a plane
which is orthogonal to an axis in an uninstalled state, and an inner
diameter φ1 of a deepest section of each of the slits 16d is larger
than an inner diameter φ2 of the dust filter 16, and is slightly
smaller than an outer diameter φ3 (refer to FIG. 2) of the sliding
portion with the dust filter 16 in the sleeve 21 of the slinger 2, in
this state. The other structures are the same as those of the first
embodiment described previously.

[0048]Accordingly, even in this state, since the inner diameter section
16a of the dust filter 16 is brought into close contact with the outer
peripheral surface of the sleeve 21 shown in FIG. 1 in a state of being
suitably pushed open, and an edge portion 16e of the deepest section in
each of the slits 16d is brought into close contact with the outer
peripheral surface of the sleeve 21 with a suitable fastening margin, the
same effects as those of the first embodiment can be achieved.